Lecture 05 - Protein synthesis: 1.Information from the DNA...

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BIOLOGY 1001: LECTURE 5 DNA STRUCTURE AND REPLICATION; PROTEIN SYNTHESIS Nucleic acids: Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Nucleic acids are long chains of nucleotides; nucleotides are composed of: I. Nitrogenous base: a.Pyrimidine (six-member ring) 1. C = Cytosine 2. T = Thymine (DNA only) 3. U = Uracil (RNA only) b.Purines (five-member ring linked to six-member ring) 1. A = Adenine 2. G = Guanine II. Five-carbon sugar (pentose) III.Phosphate group DNA is two-stranded, the strands weakly linked by pairing of complementary bases: A only pairs with T G only pairs with C DNA REPLICATION results from enzyme-assisted separation of the strands and enzyme-assisted delivery of complementary nucleotides DNA codes for RNA and proteins RNA assists in protein synthesis
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Unformatted text preview: Protein synthesis: 1.Information from the DNA is TRANSCRIBED to messenger RNA (mRNA) Pairing is the same as in replication, except A pairs with U 2.mRNA is TRANSLATED to produce protein a.mRNA CODONS are sequences of three adjacent nucleotides b.Transfer RNA (tRNA) carries an amino acid to the codon c.mRNA and tRNA are held together on a ribosome Random errors in nucleotide sequences: Each base-pair substitution is called a point mutation Accumulated base-pair substitutions indicate evolutionary relationship GENOTYPE - genetic make-up of an organism (DNA in all species except certain viruses) PHENOTYPE - the physical traits of an organism (primarily consisting of proteins)...
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